下列关于安装高处作业吊篮限位装置原则的陈述,正确的一项是()
A.应设上限位和下限位
B.应设上限位,宜设下限位
C.宜设上限位和下限位
D.应设下限位,宜设上限位
参考答案:B
Had I run out of gas, I ought to have called the garage.
A.had
B.would have
C.would
D.should have
球化不良的特征是除少量的球状石墨外,尚有少量的厚片状石墨存在。()